Soil conditioners are used to improve the quality of soil for improved plant growth and yield. It is desired that a soil conditioner be applied in a state that is readily dispersed to the soil. Thus active ingredients of soil conditioners are typically in a finely ground or powdery form. The conditioning ingredients are typically combined with a binder to form pellets for ease of handling, transportation, and dispersion to application sites.
Examples of soil conditioners include lime which contains calcium carbonate and other minerals including magnesium, and gypsum which is hydrated calcium sulfate. Lime reduces soil acidity which improves plant growth. Gypsum improves soil drainage and promotes plant growth.
An example of a binder that is combined with soil conditioners is lignosulfonate (or lignosulfate; sulfonated lignin). Lignosulfonate is a by-product of the sulfite method for manufacturing paper from wood pulp. During this process, lignin in wood is separated from cellulose and is sulfonated. The resulting sulfonated lignin by-product is an effective binder for powdery substances. WO201426048 discloses a method for producing a fertilizer wherein pellets of gypsum and a binder, such as lignosulfonate, are made. US20140030369 discloses soil amendment compositions containing lignosulfonate.
In a cellulosic ethanol process which makes use of lignocellulosic biomass as a carbon source for fermentation, whole stillage from a distillation column (beer column) is typically separated into solids (wetcake or filter cake) and liquid (thin stillage) fractions. The thin stillage is passed through evaporators producing a syrup. The filter cake and syrup are co-products of the cellulosic ethanol process. A syrup with at least about 40% solids may be burned as disclosed in US20120102823, thereby providing energy. The filter cake may also be burned to provide energy.
There remains a need for additional materials that are readily available from renewable resources, which can be used as binders in soil conditioners.